DE2253215A1 - METHOD OF MANUFACTURING AN IMPROVED DEHYDRATION CATALYST - Google Patents

Description

Process for Making an Improved Dehydrogenation Catalyst The present invention relates to the dehydrogenation of alkylaromatics to vinylaromatics, in particular a process for the production of a corresponding catalyst.

It has been found that by preparing an alkaline egg oxide catalyst using a special ratio of yellow iron oxide to red iron oxide as the starting materials, obtain a superior catalyst which has better conversion the alkyl aromatics and a high yield of the desired vinyl aromatics provides According to the process according to the invention, the new catalyst is obtained if the Fe2O3 component is a mixture of hydrated (yellow) iron oxide and anhydrous (red) iron oxide used, the 20-56 and 55-79 tissue yellow iron oxide (related on the total amount of iron oxides present) if one is under adiabatic Reaction conditions works, and the 27-40 and 79-95 wt. Yellow iron oxide (based on on the total amount of iron oxides present) if one is under isothermal Reaction conditions works. This mixture of iron oxides is mixed with a small Amount of an alkali oxide combined, preferably potassium oxide, or with an oxide former, e.g. the carbonate, also with a small amount of chromium oxide or an alkali chromate or dichromate and a suitable binder, e.g. refractory cement. The binder is used in. An amount of about 1-5, preferably 2-4, based on the Total weight of the active components and the binder. Alternatively, the catalyst contain catalytic modifiers, e.g.

Vanadium oxide or an oxide of manganese, cobalt, copper or zinc. Some of them are used in the preparation of the catalyst of the present invention Preferably about 5-15% by weight of methyl cellulose as constituents of the catalyst paste and carbon or graphite to add strength and consistency to the catalyst paste to ensure the properties when pressing and at the Improve pellet formation and the porosity of those formed during calcination Check catalyst pellets. The amount of methyl cellulose and carbon refers to the total weight of the dry ingredients of the paste, i.e. the weight of the active components and the binder, including that in the hydrated Fe203 (yellow oxide) present water.

Methyl cellulose and carbon are preferably used in such Catalysts to be used under adiabatic reaction conditions; these additives are omitted when the catalyst is under isothermal reaction conditions should be used. It is not known what the physical effects are the structure of the final catalyst through the manufacture of the catalyst paste from a special mixture of yellow iron oxide and red iron oxide. It is shown below, however, that using such a mixture within the specified proportions in combination with the other important ingredients of a self-regenerating dehydrogenation catalyst, an improved catalyst is obtained which leads to higher degrees of conversion without practically any reduction the yield occurs.

The terms yellow iron oxide used in the present application, and "hydrated Fe2O3" are synonymous and refer to the form of the Fe203, which occurs in different shades from light yellow to dark yellow-orange.

These yellow iron oxides are practically nonohydrates and have one Water content of about 13 wt., -, The terms "red iron oxide" and "anhydrous Fe2O3 "are synonymous and refer to the practically anhydrous Fe2O3, which is red until it is red-brown in color.

When using the dehydration catalyst tçJre71 in ad: i.abatic Reactors, the preferred amount of yellow oxide (based on total weight of the Fe203 used) 35-43 and 70-75 wt%.

When using the dehydrogenation catalysts in isothermal reactors (whose reaction conditions are different from the adiabatic reactors) the preferred amount of the yellow oxide is 29-35 and 83-90% by weight.

These areas are shown in FIGS. 1 and 2, namely in the dashed districts.

It should be emphasized that graphite and methyl cellulose, soft to Manufacture of the adiabatic catalysts used to manufacture åer Kataysatoren for the isothermal reactor are not used; here finds the Control the porosity by using the cement instead, which also acts as a binder works.

The reaction conditions for the adiabatic system according to the state the technique use a steam / ethylbenzene weight ratio (generally referred to as the steam / oil ratio or 3/0 ratio) of about 2-3 pounds or more Steam per pound of ethylbenzene; the hourly liquid flow rate atz (LH.S.V.) is about 0.46-0.65 (volume of hydrocarbon addition per hour per volume of the catalytic converter). In the present examples, a slightly higher speed is used used by about 1.

The steam / ethylbenzene weight ratio in the isothermal reactors is about 1, whereby the liquid throughput is usually somewhat lower than for adiabatic reactor is. In any case, the t.H.S.V. value depends on the temperature the steam used and the activity of the catalyst.

Regardless of the type of reator system used (adiabatic or isothermal) the maximum results are obtained at a conversion of 60 ß and more. The improvement achieved by the method according to the invention exists that is, the fact that the new Kftalysftoren deliver high degrees of conversion, while the Yield above Q0 $ remains.

The two forms of Po20) can be used first in the correct proportions mixed, after which the mixture with the other ingredients of the catalyst paste mixed; But you can also use the two forms of Fe203 separately from the other components then mix to form the final mixture.

The order in which the components of the catalyst paste are added is not particularly critical and depends largely on the composition of what is to be manufactured Catalyst from; in general, the water-soluble components are dissolved in water and adds the water-insoluble components to them. There must be enough water be present to form a paste.

Usually you use the water in an amount of 10-50 ß (except for the water of dehydration). To get a homogeneous mixture in the shortest possible way To get time, use about 20-30.6 water. That way you get a paste that is easy to work with, i.e. it can be pressed or closed Process pellets and dry them to get the catalyst particles. The paste can be pressed into pellets and dried, or you can partially do them first dry and then pellet the relatively dry particles.

The pellets are then in the usual manner at a temperature of Calcined about 700-10000C. If you use flammable materials, e.g. carbon, Methyl cellulose, sawdust, wood flour, etc., the calcination temperature must be sufficient to volatilize or burn out the combustible materials.

Generally, the catalyst pellets are of smaller diameter more active than the bigger ones; However, larger diameters have the advantage that the Pressure drop in the reactor is lower.

The percentage of the catalytic components can vary, depending on the number and type of components used.

The basic components are iron oxide, chromium oxide and alkali oxide (e.g. K20); they are used in an amount such that the catalyst has the following composition has: Fe203 CG-90 wt-; K2Cr207 0.5-5.0 wt. Β; K2C03 8.5-0 wt .-? 6; Cement 1.0-5.0 . It is known that chromium is either known as Ohr205 or as Can use an alkali compound, which decomposes in the heat with the formation of Cr203. Likewise, the alkali oxide or a can be used instead of alkali carbonate another compound that decomposes to oxide in the heat.

A preferred catalyst paste for the production of styrene under adiabatic conditions contains 70-80 ffi Sie203, 1-4% K2Cr207, 17-22% K2O03 and 2-4 C, o / cement. You can use up to 15%, preferably 7-10% methyl cellulose and Add graphite (based on the total amount of the other components, including the water of hydration of the yellow oxide). This addition is made for modification the pore structure of the catalyst; the substances become during the calcination substances burned away. The cement (portland or alumina) is also a pore modifier. It serves to reduce the surface area by removing the smaller pores of the catalyst clogged.

In the adiabatic system, steam is mixed with ethylbenzene and the mixture passed over the catalyst. If necessary, additional heat is added, by adding the starting components to the flow at points in the catalyst bed below, introduces steam.

In the isothermal system, the ethylbenzene is added immediately its introduction into the catalyst with steam; the catalyst is usually located in tubes in a housing, similar to the arrangement of a heat exchanger. Further Heat is supplied by passing steam or exhaust gases through the housing, which surrounds the tubes containing the catalyst. While the reaction mixture passes the catalyst, no further steam is added.

The best proportions of yellow to red oxide within the preferred ranges depend on the proportion of the total iron oxides on the promoters and modifiers involved in the formulation of the catalyst be used. These can easily be determined experimentally by the person skilled in the art will.

The invention is explained in more detail in the following examples; she show the surprising advantages of using a defined mixture of yellow iron oxide and red iron oxide compared to using either oxide alone.

Example 1 A paste is produced with a water content of 26% by weight (except the hydration water) and the äe contains 10 ß methyl cellulose and graphite. The catalyst composition has the following composition: Each 203 70.7 wt. K2C03 20.0 K2Cr207 3.0 "V205 3.0 cement 3.3 The paste is pressed into pellets and dried and then calcined at 7000C for 2 hours.

Catalyst No. 1 contains red iron oxide, and Catalyst No. 2 yellow iron oxide, the catalyst no. 3 a mixture of 40 wt .- yellow oxide and 60 wt% red oxide.

The catalysts 1, 2 and 3 are separately in an electrically heated one Stainless steel tube (2.54 cm diameter) containing 70 ml of catalyst contains. Preheated steam and ethylbenzene are passed over the catalyst bed, the temperature being between 600 and 6600C, so that the conversion occurs and is maintained. The steam / ethylbenzene weight ratio is 2: 1, the pressure 1.34 atm., the hourly liquid throughput 1.0 ml EB / ml cat./hour. The temperature of each experiment is controlled in a certain range, like this that the desired conversion is obtained. The ones obtained in various conversions The results are summarized in Table I below; Tabel I Catalyst No. Weight R 'Conversion of the selectivity of styrene ethylbenzene (yield Weight, -) 1 40 95.0 2 40 95.3 3 40 95.5 1 60 92.8 2 60 93.0 3 60 94.3 1 80 88.0 2 80 86.8 3 80 90.0 The above data shows a mixture of red and yellow oxides as a starting material in the production of dehydrogenation catalysts especially when used to convert a higher amount of ethylbenzene into styrene to convert.

Example 2 In a series of experiments, identical catalysts are used produced, but the proportion of yellow and red iron oxide is different. These catalysts are used to produce styrene; for every catalyst the value of the conversion selectivity (CSV) is determined. The formulation of the catalyst paste and their production is identical to that in Example 1.

CSV: This is a numerical value that can be obtained by adding the degree of conversion and the SeReRtivitat (yield of styrene) in a certain experiment.

In Table II is the percentage of the dehydrogenated oxide stated in the original catalyst preparation, as well as the CSV values when used of the catalyst for the production of styrene. The reaction conditions in the conversion of ethylbenzene in styrene are in testing all different catalysts constant. Danipf / oil weight ratio, i.e. ethylbenzene (EB) 2: 1, hourly liquid throughput 1.0 ml. EB / ml.

cat./h, temperature 600-560 ° C, pressure 1.34 atm.

The procedure is carried out in the specified temperature range with the various Catalysts carried out so that a selectivity of 90% styrene is obtained. The percentage conversion at this selectivity then becomes with the selectivity added so that the CSV value is obtained.

Table II Hydrated Fe203 (weight of the CSV value of total iron oxide) 0 164.5 (pure red oxide) 10 160.5 20 165.0 25 165.5 30 166.0 35 166.7 40 167.5 60 164.3 70 165.3 75 166.0 85 163.0 100 163.7 (pure yellow oxide) - the Results of Example 2 are shown in FIG.

To show that the process according to the invention also applies to catalysts The following example is useful, which contain larger amounts of iron oxide carried out. The catalysts compared here do not contain a V205 pronoter, as it was present in Examples 1 and 2.

Example 3 A manufactured according to the method according to the invention Catalyst (C) is matched with catalysts using red oxide (A "and yellow Oxide (B) compared as the only iron oxide. The three catalysts have the following Composition: Fe203 84.5% by weight K2003 10.0 K2Cr207 2.2 cement 3.3 The catalyst components are made into a paste, each containing 10% graphite and methyl cellulose contains (based on the weight of the above components); the paste is pressed to 0.5 cm pellets. This is put into an oven at room temperature, which is then inside heated from about 35 minutes to 800 ° C and about 3 1/2 hours at this temperature is held.

The pellets are then allowed to cool and 70 ml of each catalyst is added separately in a stainless steel reactor 2.54 cm in diameter.

The starting material for catalyst A is red iron oxide, for catalyst B yellow iron oxide, for catalyst C a mixture of the two oxides.

The dehydration is carried out; by getting preheated steam and passing ethylbenzene over the catalyst7 which is kept at or near 6000C. L.H.S.V .: 1.0, steam = 2: 1, pressure 1.34 atm. (these conditions are the same as in example 1 and 2).

The reactor temperature varies in a range of about 590-6200C. The performance of the catalyst is at 90% yields and degrees of conversion of 60% compared (see Table III) Table III Catalyst CSV at 60 ffi CSV at 90% conversion yield A red Fe 2 O 3 150.4 151.2 B yellow Be 2 O 5 150.9 155.0 C (75 ffi yellow + 25 be red Fe 2 O 3) 151.5 156.5 The superiority of the invention Catalyst (C) can be clearly seen whether the comparison is made at the same degree of conversion or with the same selectivity.

The reaction conditions used in the previous examples correspond to an adiabatic reactor system for the production of styrene. the Catalysts prepared by the process according to the invention can also be used in Isothermal reactors can be used in which the temperature is externally controlled is done by passing steam (or some other heat exchange medium) through an enclosure conducts, which surrounds the reactor tubes. The isothermal reaction uses less Flow rates (approx. 0.5), the steam / oil ratio is approx. 1.

The following example works under isothermal conditions, wherein the quantitative ratio of the hydrate in the preparation of various catalysts varies; the composition of the catalysts in terms of active oxides (oxides iron, potassium and chromium) and the binder (cement) are the same. Be on it indicated that the useful upper range of hydrate compared to the above Examples using adiabatic conditions is shifted upwards. The lower portion of the hydrate is practically the same, although obvious is narrowed.

The results are different from the previous examples shown. This becomes the temperature required for a particular transformation (60) determined, and temperatures are compared instead of yields. The lower the required temperature, the better the catalyst.

Example 4 A catalyst is prepared having the same composition as in Example 3, but no pore control agents (i.e. graphite or methyl cellulose). It is calcined at 9000C.

In use, the catalyst is placed in a tube of the same Size and arrangement as in example 1. The process conditions for production of styrene from ethylbenzene are those preferred for an isothermal reactor system: L.H.S.V. = 0.65, steam / oil ratio = 1.0, pressure = 1.34 atm. Flow rate and The steam / oil ratio is about half that of the adiabatic system. the Results are shown in Table IV.

Table IV wt .- / o yellow FeO at temperature (OC at 60% production des iaalysators conversion) 20 648 30 627 50 639 75 637 87 620 100 635 the above Data is also shown in FIG.

Claims (12)

P a t e n t a n s p r ü c h e 1. Process for the preparation of a catalyst for dehydrogenation from alkyl aromatics to vinyl aromatics by making a paste which- Pe203, Cr203 or an alkali chromate or dichromate that decomposes with the formation of Cr203 is an alkali oxide or an alkali salt which decomposes to form alkali oxide and contains sufficient water to pellet the paste and the pellets calcined, characterized in that the Fe2O3 component is a mixture of hydrated Fe203 and anhydrous Be203 are used, the hydrated Fe203 in an amount of 27-40 wt .-% or 79-95 wt .-% (based on the total weight the iron oxides) is present when the catalyst is in an isothermal reaction used, and wherein the hydrated Fe 2 O 3 in an amount of 20-56 or 55-79 % By weight (based on the total weight of the iron oxides) is present when the catalyst is used in an adiabatic reaction. 2. The method according to claim 1, characterized in that the hydrated Fe203 in an amount of 29-35 or 83-90 Gew0 - "', o (based on the total weight iron oxides) is used. 3. The method according to claim 2, characterized in that the catalyst composition Contains cement as a binder. 4. The method according to claim 3, characterized in that the catalyst composition Contains 1-5% by weight cement (based on the weight of the active oxides plus cement). 5. The method according to claim 3, characterized in that the catalyst paste 60-90% by weight Fe203, 0.5-5% by weight K2Cr207, 8.5-30% by weight, b K2C03 and 1-5% by weight cement contains0 6. The method according to claim 4, characterized in that the catalyst paste 70-80% by weight Fe2O3, 1-4% by weight Só S2Cr207, 17-22% by weight K2G03, 2-4% by weight cement (based on based on the total weight of the active components plus binder). 7. The method according to claim 1, characterized in that in addition Vanadium pentoxide is present as a modifier and that one is a mixture us hydrated Fe2O3 and anhydrous Fe203 are used, with the hydrated Fe2O3 in an amount of 20-56 or 65-79 G.- (based on the total weight of the existing iron oxides) is present. 8. The method according to claim 7, characterized in that) cement is present as a binder. 9. The method according to claim 8, characterized in that the catalyst composition 1-5% by weight of cement and 7-10 ffi each of methyl cellulose and graphite (based on the Weight of active oxides plus cement). 10. A process for the production of styrene from ethylbenzene, wherein one Steam and ethylbenzene over an iron oxide catalyst in a weight ratio conducts of about 2: 1, characterized in that a catalyst is used which was prepared according to the process of claims 7-9, the ethylbenzene in one introduces hourly liquid throughput of about 1.0 and a temperature of 600-660 ° C and a pressure of about 1.34 atm. used. 11. A process for the preparation of styrene from ethylbenzene, wherein one Steam and ethylbenzene through an iron oxide catalyst in a weight ratio conducts of about 1: 1, characterized in that a catalyst is used which was prepared by the process of claim 1, the Ethy3benzol in one hourly liquid oil throughput of about 0.6 and a temperature of 600-660 ° C and a pressure of about 1.34 atm. used. 12. The method according to claim 11, characterized in that the catalyst Contains cement as a binder. L e r s e i t e